A so-called rear-surface operation-type mobile electronic device has been known. For example, Unexamined Japanese Patent Application KOKAI Publication No. 2002-6988 discloses a mobile handset in which an operation pad is arranged on the rear surface of a body of the mobile handset equipped with a liquid crystal display unit, and various operation input are accomplished by causing a cursor displayed on the liquid crystal display unit to move using the operation pad.
Such a rear-surface operation-type mobile electronic device does not require a keyboard and thus can be made more compact and lightweight. In addition, this kind of mobile electronic device is convenient for a user to carry and operate.